mongodump.exe备份的原理是通过一次查询获取当前服务器快照，并将快照写入磁盘中，因此这种方式保存的也不是实时的，因为在获取快照后，服务器还会有数据写入，为了保证备份的安全，同样我们还是可以利用fsync锁使服务器数据暂时写入缓存中。

高效开源数据库(mongodb)下载地址：https://www.jb51.net/softs/41751.html

备份前的检查
> show dbs
MyDB 0.0625GB
admin (empty)
bruce 0.0625GB
local (empty)
test 0.0625GB
> use MyDB
switched to db MyDB
> db.users.find()
{ "_id" : ObjectId("4e290aa39a1945747b28f1ee"), "a" : 1, "b" : 1 }
{ "_id" : ObjectId("4e2cd2182a65c81f21566318"), "a" : 3, "b" : 5 }
>

整库备份：
mongodump -h dbhost -d dbname -o dbdirectory
-h：MongDB所在服务器地址，例如：127.0.0.1，当然也可以指定端口号：127.0.0.1:27017
-d：需要备份的数据库实例，例如：test
-o：备份的数据存放位置，例如：c:\data\dump，当然该目录需要提前建立，在备份完成后，系统自动在dump目录下建立一个test目录，这个目录里面存放该数据库实例的备份数据。

mongodump的官方说明(可通过mongodump --help查看)：
options:
 --help          produce help message
 -v [ --verbose ]     be more verbose (include multiple times for more
              verbosity e.g. -vvvvv)
 --version        print the program's version and exit
 -h [ --host ] arg    mongo host to connect to ( /s1,s2 for
              sets)
 --port arg        server port. Can also use --host hostname:port
 --ipv6          enable IPv6 support (disabled by default)
 -u [ --username ] arg  username
 -p [ --password ] arg  password
 --dbpath arg       directly access mongod database files in the given
              path, instead of connecting to a mongod server -
              needs to lock the data directory, so cannot be used
              if a mongod is currently accessing the same path
 --directoryperdb     if dbpath specified, each db is in a separate
              directory
 --journal        enable journaling
 -d [ --db ] arg     database to use
 -c [ --collection ] arg collection to use (some commands)
 -o [ --out ] arg (=dump) output directory or "-" for stdout
 -q [ --query ] arg    json query
 --oplog         Use oplog for point-in-time snapshotting
 --repair         try to recover a crashed database
 --forceTableScan     force a table scan (do not use $snapshot)

整库恢复：
mongorestore -h dbhost -d dbname –directoryperdb dbdirectory
-h：MongoDB所在服务器地址
-d：需要恢复的数据库实例，例如：test，当然这个名称也可以和备份时候的不一样，比如test2
–directoryperdb：备份数据所在位置，例如：c:\data\dump\test，这里为什么要多加一个test，而不是备份时候的dump，读者自己查看提示吧！
–drop：恢复的时候，先删除当前数据，然后恢复备份的数据。就是说，恢复后，备份后添加修改的数据都会被删除，慎用哦！

mongorestore的官方说明(可通过mongorestore --help查看)：
options:
 --help         produce help message
 -v [ --verbose ]    be more verbose (include multiple times for more
             verbosity e.g. -vvvvv)
 --version        print the program's version and exit
 -h [ --host ] arg    mongo host to connect to ( /s1,s2 for sets)
 --port arg       server port. Can also use --host hostname:port
 --ipv6         enable IPv6 support (disabled by default)
 -u [ --username ] arg  username
 -p [ --password ] arg  password
 --dbpath arg      directly access mongod database files in the given
             path, instead of connecting to a mongod server -
             needs to lock the data directory, so cannot be used
             if a mongod is currently accessing the same path
 --directoryperdb    if dbpath specified, each db is in a separate
             directory
 --journal        enable journaling
 -d [ --db ] arg     database to use
 -c [ --collection ] arg collection to use (some commands)
 --objcheck       validate object before inserting
 --filter arg      filter to apply before inserting
 --drop         drop each collection before import
 --oplogReplay      replay oplog for point-in-time restore
 --oplogLimit arg    exclude oplog entries newer than provided timestamp
             (epoch[:ordinal])
 --keepIndexVersion   don't upgrade indexes to newest version
 --noOptionsRestore   don't restore collection options
 --noIndexRestore    don't restore indexes
 --w arg (=1)      minimum number of replicas per write

单个collection备份：
mongoexport -h dbhost -d dbname -c collectionname -f collectionKey -o dbdirectory
-h: MongoDB所在服务器地址
-d: 需要恢复的数据库实例
-c: 需要恢复的集合
-f: 需要导出的字段(省略为所有字段)
-o: 表示导出的文件名

mongoexport的官方说明(可通过mongoexport --help查看)：
 --help          produce help message
 -v [ --verbose ]     be more verbose (include multiple times for more
              verbosity e.g. -vvvvv)
 --version         print the program's version and exit
 -h [ --host ] arg     mongo host to connect to ( /s1,s2 for
              sets)
 --port arg        server port. Can also use --host hostname:port
 --ipv6          enable IPv6 support (disabled by default)
 -u [ --username ] arg   username
 -p [ --password ] arg   password
 --dbpath arg       directly access mongod database files in the given
              path, instead of connecting to a mongod server -
              needs to lock the data directory, so cannot be used
              if a mongod is currently accessing the same path
 --directoryperdb     if dbpath specified, each db is in a separate
              directory
 --journal         enable journaling
 -d [ --db ] arg      database to use
 -c [ --collection ] arg  collection to use (some commands)
 -f [ --fields ] arg    comma separated list of field names e.g. -f
              name,age
 --fieldFile arg      file with fields names - 1 per line
 -q [ --query ] arg    query filter, as a JSON string
 --csv           export to csv instead of json
 -o [ --out ] arg     output file; if not specified, stdout is used
 --jsonArray        output to a json array rather than one object per
              line
 -k [ --slaveOk ] arg (=1) use secondaries for export if available, default
              true
 --forceTableScan     force a table scan (do not use $snapshot)

单个collection恢复：
mongoimport -d dbhost -c collectionname –type csv –headerline –file
-type: 指明要导入的文件格式
-headerline: 批明不导入第一行，因为第一行是列名
-file: 指明要导入的文件路径

mongoimport的官方说明(可通过mongoimport --help查看)：
 --help         produce help message
 -v [ --verbose ]    be more verbose (include multiple times for more
             verbosity e.g. -vvvvv)
 --version        print the program's version and exit
 -h [ --host ] arg    mongo host to connect to ( /s1,s2 for sets)
 --port arg       server port. Can also use --host hostname:port
 --ipv6         enable IPv6 support (disabled by default)
 -u [ --username ] arg  username
 -p [ --password ] arg  password
 --dbpath arg      directly access mongod database files in the given
             path, instead of connecting to a mongod server -
             needs to lock the data directory, so cannot be used
             if a mongod is currently accessing the same path
 --directoryperdb    if dbpath specified, each db is in a separate
             directory
 --journal        enable journaling
 -d [ --db ] arg     database to use
 -c [ --collection ] arg collection to use (some commands)
 -f [ --fields ] arg   comma separated list of field names e.g. -f name,age
 --fieldFile arg     file with fields names - 1 per line
 --ignoreBlanks     if given, empty fields in csv and tsv will be ignored
 --type arg       type of file to import. default: json (json,csv,tsv)
 --file arg       file to import from; if not specified stdin is used
 --drop         drop collection first
 --headerline      CSV,TSV only - use first line as headers
 --upsert        insert or update objects that already exist
 --upsertFields arg   comma-separated fields for the query part of the
             upsert. You should make sure this is indexed
 --stopOnError      stop importing at first error rather than continuing
 --jsonArray       load a json array, not one item per line. Currently
             limited to 16MB.

其他导入与导出操作：

1. mongoimport -d my_mongodb -c user user.dat

参数说明:

-d 指明使用的库, 本例中为” my_mongodb”

-c 指明要导出的表, 本例中为”user”

可以看到导入数据的时候会隐式创建表结构

2. mongoexport -d my_mongodb -c user -o user.dat

参数说明:

-d 指明使用的库, 本例中为” my_mongodb”

-c 指明要导出的表, 本例中为”user”

-o 指明要导出的文件名, 本例中为”user.dat”

从上面可以看到导出的方式使用的是JSON 的样式.